Molinari started the final round five shots from the lead but secured his fourth worldwide win in 10 months with a sizzling final round.

It also came with a $US1.6 million ($A2.3m) winner's prize.

Molinari became Italy's first major champion when he claimed last year's British Open - in addition to victories at the European Tour's flagship BMW PGA Championship and his maiden PGA Tour title at the Quicken Loans event.

The 5-foot-8 golfer grew up in northern Italy's Turin, home of European football powerhouse Juventus FC.

But golf was not a popular sport.

"(Access) wasn't particularly cheap or easy; we were just lucky our family was into golf and that's how we got into it," Molinari said.

"(Italians are not) exposed to that much golf, but 'Arnie' was such a global icon that this tournament was one that we watched, my brother and I, at home many times.

"We have the (2022) Ryder Cup coming (to Italy), so hopefully they can make the most of it.

"I hope kids are watching me, like I was watching Costantino (Rocca) many years ago and, in a few years from now, I'll be sitting on the couch watching some other Italian kid playing on the PGA Tour."

Meanwhile, Australia's Aaron Baddeley started the final day just two shots from the lead but faded with a 74.

Baddeley squandered a chance to claim his first PGA Tour win since July 2016 and claim one of the automatic exemptions to this year's British Open - which were awarded to the top-three finishers not already exempt.

They went to South Koreans Im and Sung Kang and American Keith Mitchell.

Australian Marc Leishman, the 2017 winner at Bay Hill, signed off with a respectable 70 to earn a four-under total and a share of 23rd.

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